Stable isotopic response to late Eocene extraterrestrial impacts

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doi: 10.1130/2009.2452(06)
Author(s): Pusz, Aimee E.; Miller, Kenneth G.; Wright, James D.; Katz, Miriam E.; Cramer, Benjamin S.; Kent, Dennis V.
Author Affiliation(s): Primary:
Rutgers University, Department of Earth and Planetary Sciences, Piscataway, NJ, United States
Osservatorio Geologico di Coldigioco, Italy
Rensselaer Polytechnic Institute, United States
University of Oregon, United States
Volume Title: Late Eocene Earth; hothouse, icehouse, and impacts
Volume Author(s): Koeberl, Christian, editor; Montanari, Alessandro
Source: Special Paper - Geological Society of America, Vol.452, p.83-95; Geological Sociaty of America (GSA) Penrose conference, Ancona, Italy, Oct. 3-6, 2007, edited by Christian Koeberl and Alessandro Montanari. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0072-1077. ISBN: 978-0-8137-2452-2 CODEN: GSAPAZ
Note: In English. NSF grants OPP-0424940, EAR-06-06693, and OCE-06-23256. 91 refs.; illus., incl. 4 tables, sketch map
Summary: We evaluated the age of two Upper Eocene impact ejecta layers (North American microtektites linked to the Chesapeake Bay impact structure and clinopyroxene [cpx] spherules from the Popigai crater) and the global effects of the associated impact events. The reported occurrence of cpx spherules from the Popigai impact structure at South Atlantic ODP Site 1090 within the middle of magnetochron C16n.1n yields a magnetochronologic age of 35.4 Ma. We generated high-resolution stable isotope records at Sites 1090, 612 (New Jersey slope), and Caribbean core RC9-58 that show: (1) a 0.5 ppm δ13C decrease in bulk-carbonate at Site 1090 coincident with the Popigai cpx spherule layer, and (2) a 0.4 ppm-0.5 ppm decrease in deep-water benthic foraminiferal δ13C values across the Popigai impact ejecta layer at Site 612 and core RC9-58. We conclude that the δ13C excursion associated with Popigai was a global event throughout the marine realm that can be correlated to magnetochron C16n.1n. The amplitude of this excursion (∼0.5 ppm) is within the limits of natural variability, suggesting it was caused by a decrease in carbon export productivity, potentially triggered by the impact event(s). North American microtektites associated with the Chesapeake Bay impact occur stratigraphically above the Popigai cpx spherules at Site 612 and core RC9-58. We found no definite evidence of a δ13C anomaly associated with the North American microtektite layer, though further studies are warranted. High-resolution bulk-carbonate and benthic foraminiferal δ18O records show no global temperature change associated with the cpx spherule or North American microtektite layers.
Year of Publication: 2009
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Anomalinidae; Asia; Atlantic Ocean; C-13/C-12; Carbon; Cassidulinacea; Cenozoic; Chemostratigraphy; Chesapeake Bay impact structure; Cibicidoides; Commonwealth of Independent States; DSDP Site 612; Deep Sea Drilling Project; Ejecta; Eocene; Foraminifera; IPOD; Impacts; Invertebrata; Isotope ratios; Isotopes; Leg 177; Leg 95; Marine environment; Microfossils; North Atlantic; O-18/O-16; ODP Site 1090; Ocean Drilling Program; Oxygen; Paleoenvironment; Paleogene; Popigay Structure; Protista; Rotaliina; Russian Federation; South Atlantic; Stable isotopes; Tertiary; Upper Eocene
Coordinates: S425449 S425449 E0085359 E0085359
N384912 N384913 W0724625 W0724626
Record ID: 2009074332
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